Although the size of portable electronic devices continues to shrink, their energy requirements often do not comparably decrease. For example, a next-generation MEMS accelerometer may have a volume that is 10 percent smaller and yet, require are only 5 percent less power than the prior generation MEMS accelerometer. In that case, more of the MEMS die may be used for energy storage. Undesirably, this trend can limit miniaturization and applicability of such electronic devices.
The art has responded to this problem by developing chip-level super-capacitors (also known as “micro super-capacitors”), which have much greater capacitances than conventional capacitors. In a manner similar to conventional capacitors, super-capacitors generally have higher power densities than batteries. Undesirably, however, super-capacitors generally have lower storage capabilities than batteries.